The invention relates generally to flushing apparatus for water flow control adopted for use in toilets, and more particularly, to the valve means which controls the outflow of the flushing water into the toilet bowl.
It is well known that a great waste of treated water usually occurs when flushing a usual residential type toilet. Most toilet flush tanks have a capacity of approximately six gallons of water, all or substantially all of which is discharged upon each operation of the tank flush valve. In those cases where only a small amount of flushing water is required, for example, to flush liquid waste, the complete discharge of the flush tank contents results in an unnecessary waste of water. It has long been recognized that water can be conserved in the latter case by providing a mechanism that will discharge only that amount of water from the flush tank necessary to the sufficiently flush the liquid wastes. For example, a flush tank discharge of approximately two gallons would normally be sufficient to fully flush liquid waste under usual conditions.
Many prior workers in the art have developed flush mechanisms capable of metering the water utilized in the flush or capable of flushing either the full contents of the tank or one half the contents of the tank upon suitable operation of the handle. U.S. Pat. Nos. 1,960,864, 1,992,381, 2,532,977, 2,636,184, 2,702,908, 2,879,522, 2,963,710, 3,093,833, 3,365,730, 3,546,715, 3,719,957, 3,745,591, and 3,894,299 are exemplary of prior art devices which have been developed in an attempt to solve the problem to which the present application is directed. These devices have all proved to be deficient in one or more important considerations such as complexity of structure, the requirement that substantial portions of the prior mechanism be abandoned, that the devices were not readily compatible with existing equipment, or that installation procedures were so complicated that only skilled workers could be employed to make the installation.